Tubular shaft instrument

ABSTRACT

The invention relates to tubular shaft instruments, which are provided with a handle, a tubular shaft and a tool head. The tool head usually has two mouth parts, which can be displaced in relation to one another for gripping and fixing tissue. The invention discloses a slotted guide system for forming the articulation, said system having a virtual fulcrum outside the tubular shaft instrument.

BACKGROUND OF THE INVENTION

The invention relates to a tubular shaft instrument.

In modern medicine, attempts are generally made to keep the damage tointact tissue to a minimum. Thus, when circumstances permit, minimallyinvasive surgery is usually the preferred method used to perform anoperative intervention. Small incisions and little trauma to the tissuelead to a lower sensation of pain after the operation and to rapidrecovery and mobilisation of the patient. This also applies tolaparoscopic surgery during which complex operations are performed inthe abdominal cavity.

Operations of this type and the instruments required for them present aparticular challenge to the manufacturers of medical instruments as themajority of the operative steps are performed in very restricted spacesand without direct visual contact. Thus the medical instruments usedmust not only be able to operate in the smallest spaces but must alsofunction so reliably that visual monitoring is superfluous. Theinstruments are preferably constructed such that even without visualcontact the operating surgeon always has feedback which enables him todraw conclusions about the progress of the operation.

Tubular shaft instruments are known which comprise a handle, a tubularshaft and at least two mouth parts. These tubular shaft instruments aresuitable for gripping and fixing tissue. These tubular shaft instrumentsfrequently have other functionalities. Thus, EP 1 211 995 B1, forexample, discloses a tubular shaft instrument having corresponding mouthparts which applies high-frequency (“HF”) current to the fixed tissue inorder to coagulate it. It is also known to provide such tubular shaftinstruments having a cutting device for separating the gripped tissue.

As tubular shaft instruments are used in very restricted regions of thebody, they must be kept as small as possible. Nevertheless, as alreadyobserved, a reliable method of functioning and a high level offunctionality must be guaranteed. Thus, amongst other things, it isproblematic to ensure a sufficiently steady transmission of force foroperating the mouth parts.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in the following based on embodimentswhich will be explained in greater detail by means of drawings.

FIG. 1 illustrates a tubular shaft instrument for separating tissueaccording to a disclosed embodiment.

FIG. 2 illustrates the tool head of the tubular shaft instrument fromFIG. 1, comprising a first and a second mouth part according to adisclosed embodiment.

FIG. 3 illustrates the second mouth part in a perspective lateral viewaccording to a disclosed embodiment.

FIG. 4 illustrates the second mouth part in a view from above accordingto a disclosed embodiment.

FIG. 5 illustrates the second mouth part in a lateral view according toa disclosed embodiment.

FIG. 6 illustrates the first mouth part in a perspective lateral viewaccording to a disclosed embodiment.

FIG. 7 illustrates the first mouth part in a view from above accordingto a disclosed embodiment.

FIG. 8 illustrates the first mouth part in a lateral view according to adisclosed embodiment.

FIG. 9 illustrates a schematic diagram of two different articulationsaccording to a disclosed embodiment.

FIG. 10 illustrates a cross-section through the tool head from FIG. 2with a cutting device according to a disclosed embodiment.

FIG. 11 illustrates a schematic diagram of the cutting device accordingto a disclosed embodiment.

FIG. 12 illustrates a schematic view of the cutting device in a tubularshaft of a tubular shaft instrument according to a disclosed embodiment.

FIG. 13-15 illustrate three embodiments of a cutting blade according toa disclosed embodiment.

FIG. 16 illustrates a block diagram of an incision monitoring deviceaccording to a disclosed embodiment.

FIG. 17 illustrates a perspective view of a tool head in an openposition according to a disclosed embodiment.

FIG. 18 illustrates the tool head from FIG. 17 in a closed positionaccording to a disclosed embodiment.

FIG. 19 illustrates the second mouth part with tension strip accordingto a disclosed embodiment.

FIG. 20 illustrates the second mouth part (further embodiment) in aperspective lateral view according to a disclosed embodiment.

FIG. 21 illustrates section through the second mouth part from FIG. 20according to a disclosed embodiment.

FIG. 22 illustrates a schematic lateral view of the tubular shaftinstrument according to a disclosed embodiment.

The same reference numerals are used in the following description foridentical parts and parts acting in an identical manner.

DETAILED DESCRIPTION OF THE INVENTION

An object of the present invention is to provide a tubular shaftinstrument, which is easy to produce, has a long service life and hasextremely functional characteristics.

This object is achieved by a tubular shaft instrument which comprises:

-   a tubular shaft,-   a first and a second mouth part on a distal end of the tubular shaft    each having at least one clamping surface, and-   at least one articulation for rotatably supporting the mouth parts    in such a manner that the mouth parts may be brought from an open    position into a closed position in order to fix a tissue, whereby    the articulation is designed in such a manner that a fulcrum of the    articulation is located outside the mouth parts and the distal end    of at least one mouth part is displaceable away from the distal end    of the tubular shaft on opening of the mouth parts.

A substantial idea of the present invention is thus to provide anarticulation by means of which the mouth parts are rotatablydisplaceable in relation to each other about a fulcrum. This fulcrum isultimately virtual and is located outside, preferably above the oblongmouth parts. Due to this relocated virtual fulcrum, at least one of thetwo mouth parts experiences not only a rotary motion but also atranslation motion.

The translatory movement is oriented such that on opening of the mouthparts, the distal tip of one of the mouth parts travels distally inrelation to the tubular shaft instrument in sections at least. Amovement in the opposite direction takes place on closing. Thus themoving mouth part feeds tissue, which is located between both mouthparts, towards the tubular shaft on closing. Thus a larger area oftissue may be gripped.

In addition, it is possible due to relocation of the fulcrum to ensureimproved transmission of forces. Since the control cable used to operatethe displaceable mouth part is usually attached directly to said mouthpart, the further the attachment point is from the fulcrum, the greaterthe supporting lever effect for operating the mouth parts.

Preferably, the articulation includes a slotted guide system, i.e. atleast one of the two mouth parts is guided by means of a permanentlypredefined structure. In this case the slotted guide system determinesthe displacement of the relevant mouth part. Limited by appropriatemeans, the mouth part glides along a profile which gives rise to thetranslatory and rotary motion.

Preferably, the articulation includes an articulation guide on one ofthe two mouth parts and at least one rail or groove on the other of thetwo mouth parts. In this case the rail or groove prescribes thedisplacement path of the relevant mouth part. The articulation guideengages in the rail or groove and guides the mouth part along thedisplacement path. Usually, such slotted guide systems have a broadlypronounced contact region by way of which the sections of thearticulation, which are displaceable in relation to one another, engagewith one another. Thus such articulations are significantly more stableand can absorb greater forces. As there is no transmission of force at asingle point, these articulations usually have a longer service life.

In a preferred embodiment, the tubular shaft instrument comprises atleast two partial articulations, which are spaced apart from one anotherto form a passage disposed preferably centrally between thearticulations. A further advantage of the slotted guide system is thatthis may be disposed in a relatively space-saving manner. A particularlypositive effect arises if at least two partial articulations are used inorder to guide the mouth part. The twin design is not only particularlystable but it also enables the provision of passages through the actualcentre of the articulation in which supply lines or additionalinstruments, such as a blade for separating tissue, may be guided.

Preferably, the tubular shaft instrument includes a blade for separatingthe fixed tissue. This blade may be guided by means of a suitable guidedevice through the tissue fixed by means of the mouth parts. Thepassages described make it possible to position the guide directlythrough the centre of the articulation.

Preferably, at least one mouth part comprises a blade guide for theblade. Thus the mouth part, for example, is designed in pairs in such amanner that said blade is guided centrally between the adjacent sectionsof the mouth part. This prevents torsion or tilting of the blade orcutter.

Preferably, one of the two mouth parts is rigidly connected to thetubular shaft. Although it is conceivable to attach both mouth partsrotatably to the tubular shaft and thus to ensure the opening andclosing of both mouth parts, It is better, however, to join one of thetwo mouth parts directly to the tubular shaft so that this mouth partconstitutes an extension of the tubular shaft. The second mouth part maythen be attached by means of the articulation either to the tubularshaft, or to the other mouth part. Due to the rigid connection, thetubular shaft instrument can be more easily and securely operated.

Preferably, a substantially linearly displaceable strip or a forcetransmission device is provided for opening and closing of a mouth partto be displaced, said strip or device being attached by means of aresilient end section on the mouth part to be displaced. In a preferredembodiment, this is a tension strip, the end section of which ispermanently connected to the mouth part. The strip that is bendableabout the fulcrum winds itself around the mouth part on rotationalmovement of the mouth part about the virtual fulcrum. The push and pullmovements, which are transmitted by the force transmission element tothe mouth part to be displaced, thus always act tangentially to a circleabout the fulcrum. With a convex design of the mouth part to bedisplaced, on the side on which the actuating element rests, there is aguarantee of a regular transmission of force regardless of the positionof the mouth part to be displaced.

The strip is preferably made of spring steel.

Preferably, the strip is attached on the mouth part by means of welding,whereby the weld preferably runs out of square or curved in relation toa longitudinal axis of the strip, that is to say not at right anglesthereto. The strip is thus disposed in such a manner on the mouth partto be displaced that the latter's longitudinal axis lies substantiallyperpendicular to the fulcrum. The weld runs along the fulcrum butdescribes a curve or angle such that the weld is formed to be as long aspossible. Thus the effective force is distributed over as long adistance as possible. As a result of this, the device's durability maybe increased significantly. Alternatively, the weld may have acorrugated shape.

In a further embodiment, a pin is inserted into a hole in the tensionstrip and additionally welded in place. The mouth part to be displacedthus includes a tension strip pin and the tension strip has acorresponding drilled hole.

Preferably, at least one of the clamping surfaces includes an electrodefor coagulation of the fixed tissue. The tubular shaft instrument isthus a monopolar or bipolar terminal, by means of which the tissue fixedbetween the clamping surfaces is not only mechanically but alsoelectrically cauterised.

Preferably, at least one of the mouth parts is made of electricallyinsulating material, in particular of ceramic material, in the region ofthe articulation at least. The mouth parts may thus be cast andsubsequently sintered. Manufacture by the injection moulding method isconceivable. This type of production is to be preferred particularlywhen forming said rail or groove, that is to say the articulation. Byforming the articulation at least in sections from an electricallyinsulating material, the clamping surfaces at least of the mouth partsare electrically insulated against each other and may be used withoutfurther measures as electrodes for coagulation.

FIG. 1 provides a rough overview of an embodiment of a tubular shaftinstrument 20 according to the invention. It shows three functionalcomponents of the tubular shaft instrument 20, a handle 110, a longishtubular shaft 24 and a tool head 30 disposed on the distal end of tubeshaft 24. Tool head 30 provides the tubular shaft instrument's actualfunctionality. It is used for cutting and/or coagulating tissue. Handle110 controls the movement of tool head 30. In particular, mouth parts10, 10′ (cf. FIG. 2) may be closed as well as opened by means of handle110 for fixing, coagulating and cutting tissue.

FIG. 2 shows an embodiment of a tool head 30 according to the invention,comprising a first mouth part 10 and a second mouth part 10′. Firstmouth part 10 is an oblong body having on its side facing tubular shaft24 an adapter 25, which is rigidly joined to said tubular shaft 24.Second mouth part 10′ is attached to first mouth part 10 by way of anarticulation 40 and may be brought from an open position for seizing thetissue into a closed position for fixing the tissue. Articulation 40 isdesigned such that a virtual fulcrum 1 or pivot is located outside firstand second mouth parts 10, 10′. Unlike conventional articulations 40 forsuch instruments, fulcrum 1 is not, therefore, located in the regionwhere mouth parts 10, 10′ engage or in tubular shaft 24 close to thelongitudinal axis of tube shaft 24. The mechanism of articulation 40illustrated acts such that a virtual fulcrum 1 is created above the sideof the tubular shaft instrument which faces second mouth part 10′.

The particular advantages of such a relocated fulcrum 1 are shown on thebasis of the schematic diagrams of FIG. 9. Illustrated in the topleft-hand corner is a conventional articulation, the fulcrum 1 of whichis located substantially on the longitudinal axes of mouth parts 10 and10′. In the open position, tip 16′ of second mouth part 10′ is offsetbackwards in relation to tip 16 of first mouth part 10. However, this isnot the case with articulation 40 according to the invention, which isshown schematically in the other two diagrams of FIG. 9. Here fulcrum 1is located noticeably above the longitudinal axes of both oblong mouthparts 10, 10′. With the same opening in respect of the angle formed byfirst mouth part 10 in relation to second mouth part 10′, tip 16′ ofsecond mouth part 10′ is located substantially on or in front of aperpendicular straight line through tip 16 of first mouth part 10 evenin the open state. If second mouth part 10′ is opened in relation tofirst mouth part 10, there is thus not only a rotary displacement duringwhich the relative alignment of second mouth part 10′ changes inrelation to first mouth part 10 but there is also a longitudinaldisplacement of second mouth part 10′ which is oriented distally, thatis to say parallel to the longitudinal axis of first mouth part 10 inthe direction of its tip 16. Conversely, during a closing movement ofmouth parts 10, 10′, there is a longitudinal displacement of secondmouth part 10′ in the proximal direction. As a result of this, tissuewhich is located between both mouth parts 10, 10′, is ultimately drawninto tool head 30 (see FIG. 2). Furthermore, according to the invention,the lift of second tip 16, that is to say the distance between first andsecond tip 16, 16′, is considerably greater with the same opening angle(cf. FIG. 9, right-hand side). In one embodiment, the length of mouthparts 10, 10′ in relation to the distance of the longitudinal axis offirst mouth part 10 to the fulcrum is in the ratio of approx. 10:1.Whilst in FIG. 9 relocated fulcrum 1 is achieved, for the sake ofclarification, by way of extensions attached vertically on the proximalends of mouth parts 10, 10′, in a preferred embodiment the formation offulcrum 1 is purely virtual. This virtual design is achieved by aslotted guide system as is explained below on the basis of FIGS. 3-8.Thus, as shown in FIG. 3, second mouth part 10′ has two curvedarticulation guide rails 41, 41′ on its proximal end opposing tip 16″.Seen from above (c. FIG. 4), these articulation guide rails 41, 41′ runsubstantially parallel along the longitudinal axis of second mouth part10′ and are spaced apart to form a channel.

Seen from the side (cf. FIG. 5), second mouth part 10′ has aspoon-shaped profile. The proximal end of second mouth part 10′, inparticular articulation guide rails 41, 41′, thus each have on theirupper side a concave section 43, 43′, which engages with first mouthpart 10. As can be seen from FIG. 6, to achieve this mouth part 10 hastwo articulation guide pins 42, 42′, each of which has a convexstructural section. During the opening and closing movement of mouthparts 10, 10′, concave section 43 of first articulation guide rail 41slides over the adjacent, convex section of first articulation guide pin42 and concave section 43′ of second articulation guide rail 41* slidesover the adjacent, convex section of second articulation guide pin 42′.The curvature of concave sections 43, 43′ of both articulation guiderails 41, 41′ and the corresponding sections of articulation guide pins42, 42′ are determining for the position of virtual fulcrum 1. With amore pronounced curvature, fulcrum 1 lies closer to tool head 30 thanwith a less pronounced curvature. The effects described in respect ofFIG. 9 occur correspondingly more or less pronounced.

Compared to articulations that only have a single-point connection, theguide mechanisms or articulation 40 additionally have the advantage ofhigh stability. Due to the convex and concave sections which engage witheach other, a large-area contact region is formed and articulation 40can absorb significantly more force than an articulation with asingle-point connection. To further stabilise articulation 40, firstmouth part 10 (see FIGS. 6-8) comprises a first articulation guidebearing 46 and a second articulation guide bearing 46′. Likearticulation guide pins 42, 42′, articulation bearings 46, 46′ areattached alternately on the inside of the sidewalls of first mouth part10.

First articulation guide bearing 46 and first guide pin 42 are spacedapart such that they accommodate first articulation guide rail 41 in thespace between them. First articulation guide bearing 46 has a concavecross-section, which engages with convex section 44 of firstarticulation guide rail 41. On opening and closing tool head 30, firstarticulation guide rail 41, guided by first guide pin 42 and firstarticulation guide bearing 46, rotates about fulcrum 1 (see FIG. 5).

Likewise, second articulation guide rail 41′, guided by second guide pin42′ and articulation guide bearing 46′, rotates about fulcrum 1 (seeFIG. 5). For this, second articulation guide rail 41′, secondarticulation guide pin 42′, a convex section 44′ of second articulationguide rail 41′ and second articulation guide bearing 46′ are designedand disposed symmetrically to first articulation guide rail 41, firstarticulation guide pin 42, convex section 44 of first articulation guiderail 41 and first articulation guide bearing 46.

As shown in FIG. 10, a tension strip 27 is attached on the proximal endof second mouth part 10′. More precisely, it is attached approximatelycentrally on convex sections 44, 44′ of articulation guide rails 41,41′. To achieve this, articulation guide rails 41, 41′ have a profilefor forming an abutting edge 2 (FIG. 5). Preferably, this abutting edge2 does not run in a straight line parallel to fulcrum 1 but is designedin a semi-circular shape (cf. FIG. 19). Due to this elongated abuttingedge 2, along which second mouth part 10′ and tension strip 27 arewelded, the transmission of force into tension strip 27 is homogenisedand the tensile and flexural loading capacity of the weld issignificantly increased. In alternative embodiments, acute-angled weldsor welds with multiple serrations, which provide a comparable result,are conceivable. Tension strip 27 is substantially wider than it isthick parallel to fulcrum 1. This ensures resilience and bendability oftension strip 27 on rotation of second mouth part 10′. In thelongitudinal direction of the tubular shaft instrument, however, tensionstrip 27 is relatively stiff such that shear forces may also begenerated.

Alternatively, second mouth part 10′, as shown in FIGS. 20 and 21, has atension band pin 47, which runs substantially radially to fulcrum 1.This tension strip pin 47 is disposed centrally between convex sections44, 44′ of articulation guide rails 41, 41′ and is accommodated in ahole of tension strip 27. Thus a permanent connection is created betweenmouth part 10′ and tension strip 27. Additional welding increases thestability of the joint.

By attaching a first end of tension strip 27 to convex sections 44, 44′of articulation guide rails 41, 41′, it is ensured that the tensileforce exerted by means of tension strip 27 always acts substantiallytangentially to the circular motion of curved articulation guide rails41, 41′ about fulcrum 1. Thus a uniform transmission of forceindependent of the opening angle is assured. A second end of tensionstrip 27 is operatively connected to handle 110 and may be displaced bymeans of a control device provided thereon. Due to virtual fulcrum 1,which, as already explained, is located outside and above mouth parts10, 10′, the distance between fulcrum 1 and the first end of tensionstrip 27 is significantly greater than the distance achieved with normalarticulations. Thus the embodiment of the tubular shaft instrumentdescribed has a significantly higher leverage by means of which secondmouth part 10′ may be moved over tension strip 27.

Both mouth parts 10, 10′ each have a clamping surface 12, 12′ for fixingthe tissue. First mouth part 10 thus has, on a distal section, a firstclamping surface 12 which faces upwards. First clamping surface 12 isformed substantially concave transverse to the longitudinal axis offirst mouth part 10. In the closed state of tool head 30, convex secondclamping surface 12′ of second mouth part 10′ lies substantiallyparallel to this first clamping surface 12.

In the embodiment described, these clamping surfaces 12, 12′ are notonly suitable for securely fixing the tissue to be cut later, they alsoform the electrodes for a coagulation process. To achieve this, sectionsof clamping surfaces 12, 12′ are electrically conductive and connectedvia printed conductors to a high-frequency current source, which is alsocontrollable byway of handle 110. Thus the tissue gripped may becauterised to such an extent prior to the cutting procedure thatseparation is possible without bleeding. Preferably, sections at leastof mouth parts 10, 10′ are manufactured from ceramic material by theinjection moulding method. Thus the guide elements, in particulararticulation guide rails 41, 41′ and articulation guide pins 42, 42′ ofarticulation 40, are easy to form. Articulation 40 of ceramic materialforms an electrical insulation between mouth parts 10, 10′, inparticular between their electrodes for coagulation.

In the present embodiment, the actual mechanical cutting process takesplace after coagulation. To achieve this, a cutting device 50 is movedparallel to a fixing plane x-y (cf. FIG. 11), which is defined byclamping surfaces 12, 12′. This cutting device 50 comprises a blade 51for separating the tissue in addition to a guide wire 52 by means ofwhich a displacement of blade 51 in the longitudinal direction of thetubular shaft instrument (x-axis) is possible.

Prior to the cutting process, blade 51 is drawn back so far towardstubular shaft 24 that premature injury of the tissue is not possible.Preferably, the blade in first mouth part 10 is at the level ofarticulation guide pins 42, 42′. From this starting position, blade 51is brought onto fixing plane x-y by way of a ramp 55 integrated insecond mouth part 10′ (cf. FIG. 4 for this). This ramp 55 is locatedbetween the two articulation guide rails 41, 41′. Second mouth part 10′provides a blade guide 53 for the displacement of blade 51 or thecutter. This blade guide 53 is an oblong opening extending along thelongitudinal axis of second mouth part 10′. In order to hold blade 51perpendicular to fixing plane x-y, second mouth part 10′ has in itscentral region side parts 60, 60′, which are disposed parallel to eachother in such a way that they form a channel extending lengthways. Blade51 or the cutter is guided in this channel.

After closing mouth parts 10, 10′, blade 51 thus glides out of itsstarting position over ramp 55 into said channel and may there be pulledor pushed distally and proximally over the tissue. Blade 51 is preloadedin relation to fixing plane x-y in order to ensure that thisdisplacement separates the tissue step by step. A preloading deviceexerts a force perpendicular to fixing plane x-y, which presses blade 51against the plane. This force is built up via the resilience of guidewire 52 and its curvature. As can be seen from FIG. 12, guide wire 52 iscurved perpendicular to fixing plane x-y in the plane preloaded by blade51. A crimp 56 is located in a front section of guide wire 52. Crimp 56is integrated in guide wire 52 in such a manner that in the fullyextended state of cutting device 50, that is to say when blade 51 is atthe distal end of mouth parts 10, 10′, the crimp in tubular shaft 24 islikewise at the distal end of said shaft. Crimp 56 is used to transferat least part of the force exerted by the curvature of guide wire 52perpendicular to fixing plane x-y to tubular shaft 24 and hascorresponding contact points. The curvature of guide wire 52 is providedsuch that if the proximal end of the guide wire runs parallel to tubularshaft 24, the distal end of unattached guide wire 52 is curved downwardsand blade 51 lies at least partially below fixing level x-y. Guide wire52 is operatively connected to handle 110 in such a manner that blade 51can be moved back and forth in tool handle 30 by means thereof.

The most varied embodiments are conceivable in respect of the design ofblade 51. These will be described in the following on the basis of FIGS.13, 14 and 15. One idea of the invention is that blade 52 has at leastone section which runs substantially parallel to fixing plane x-y andthus parallel to the fixed tissue. Consequently, during the cuttingprocedure blade 51 glides over the tissue until it is completelyseparated. Unlike in conventional cutting procedures, it can thus beensured that even when blade 51 is blunt the tissue will be separatedand will not be crushed due to the mechanical pressure. The section ofthe cutting blade formed parallel to fixing plane x-y likewise has theadvantage that blade 51 rests on the tissue not only at a point butusually over a longer region. Therefore wearing of blade 51 at certainpoints is prevented.

FIG. 13 shows a semicircular blade 51, having a convex curvature. Blade51 is disposed on the underside of guide wire 52. It has a bladecurvature 54 distal and proximal to the tubular shaft instrument.

FIG. 14 shows a blade 51, comprising two semicircles each disposed onebehind the other.

FIG. 15 shows a blade 51, having a blade curvature 54 distally, and asection perpendicular to guide wire 52 proximally.

Preferably, blade 51 is microtoothed overall.

In an alternative embodiment (cf. FIG. 10 for example), guide wire 52 isa rail. The rail may be designed in such a manner that it has the samefunctionality as guide wire 52. Preloading in relation to fixing planex-y may be achieved by means of the rails intrinsic resilience or bymeans of a separate device (e.g. a spring).

The advantageous cutting device 50 of the invention has been describedso far in conjunction with the advantageous articulation shape. Bothinventions, however, may also be executed separately from one another.

Thus, FIGS. 17 and 18, for example, show cutting device 50 in a toolhead 30, whereby second mouth part 10′ is not in operative connectionwith first mouth part 10 by way of a slotted guide system. Here fulcrum1 lies substantially on the longitudinal axis of mouth parts 10, 10′.

In one embodiment according to the invention, the tubular shaftinstrument further comprises a cut monitoring device. This determineswhen the tissue between the two clamping surfaces 12, 12′ is completelyseparated. In the embodiment, blade 51 rests on first clamping surface12 when the tissue is completely separated. As clamping surface 12comprises an electrode for coagulation, it is electrically conductive inparts at least. According to the invention, at least one section ofblade 51, which mechanically contacts separating surface 12 when thetissue is separated, is likewise formed of electrically conductivematerial. The electrical contact between blade 51 and clamping surface12 is determined by means of a cut monitoring device. The gripped tissueis deemed to be completely separated when a continuous electricalcontact exists between blade 51 and clamping surface 12 during acomplete cutting movement by tip 16′ of second mouth part 10′ up to ramp55. As can be seen from FIG. 16, the cut monitoring device comprises aprocessing unit 100, a display device 101, a switch 103 and a travelsensor 102 for determining and displaying the progress of the cuttingprocedure. Travel sensor 102 determines the position or displacement ofblade 51 and consequently helps to define an observation period thatpreferably covers a complete blade movement. Switch 103 is formed in thesimplest case by means of electrically conductive blade 51 and firstclamping surface 12. As the tissue to be cut has a certain electricalconductivity, electric switch 103 is only deemed to be closed when alow-ohm connection exists between clamping surface 12 and blade 51. Acorresponding device is connected upstream of processing unit 100. Ifprocessing unit 100 ascertains that there is a continuous low-ohmcontact between blade 51 and clamping surface 12 during a completeobservation period, it indicates to the user by means of display device101 that the gripped tissue has been separated completely. Thereforecutting device 50 is treated with care since the displacement of blade51 over clamping surface 12 without tissue sandwiched between damagesthe device.

Alternatively, it may also be constantly indicated to the user whetherthere is a direct mechanical contact between blade 51 and clampingsurface 12. As the user performs the movement of blade 51 manually, hecan draw conclusions independently as to whether the tissue isadequately separated.

In a further embodiment, travel sensor 102 comprises two electricalcontact regions on the distal and proximal end of blade guide 53, whichare designed in such a manner that it is possible to determinecontacting between blade 51 and the distal contact region as well asbetween blade 51 and the proximal contact region. Processing unit 100can thus determine the start and end of the observation interval.

FIG. 22 shows a schematic detail view of handle 110 from FIG. 1. Handle110 comprises a handle body 117 on the underside of which a first handlelever 122 is integrally formed. This handle lever 122 has an opening forreceiving a plurality of fingers, preferably the middle, ring and littlefinger. A second handle lever 122′ is rotatably joined to handle body117 close to first handle lever 122. Mouth parts 10, 10′ of tool head 30may be opened and closed by means of a displacement of second handlelever 122′ relative to first handle lever 122 proximally and distally.Handle levers 122, 122′ form a hand trigger 120 and can thus be graspedin the user's hand such that the entire tubular shaft instrument can beguided with one hand. To achieve this, the hand encloses sections ofhandle lever 122, 122′. Located on the end of second handle lever 122′facing away from handle body 117 is an extension which engages in atoothed rack 124. This toothed rack 124 is attached at a right angle tothe longitudinal axis of first handle lever 122 on its end facing awayfrom handle body 117. The toothing of toothed rack 124 is designed insuch a manner that second handle lever 122′ can be moved step by steptowards handle lever 122 and the position correspondingly set remainswithout the continued exertion of a force. In order to release thisfastening of handle levers 122, 122′ to each other, toothed rack 124 ispressed away from extension 125 in such a manner that they are no longerengaged.

Moreover, handle 110 has a finger trigger 130, which is likewiserotatably attached to handle body 117. Cutting device 50, in particularblade 51, may be displaced distally by operating finger trigger 130. Aspring element (not illustrated) inside handle body 117 returns fingertrigger 130 to its starting position after operation, as a result ofwhich cutting device 50 is displaced proximally. Finger trigger 130 isdisposed distally in front of first handle lever 122 in such a mannerthat finger trigger 130 can be operated with the first finger ongrasping handle levers 122, 122′.

Handle 110 has a momentary contact switch 116 on the proximal side ofhandle body 117, which controls the coagulation current. In analternative embodiment, it is possible in place of momentary contactswitch 116 to provide a control device having a plurality of actuatingelements by means of which a plurality of coagulation modes may beselected and performed. It is likewise conceivable to provide displaydevice 101 on handle body 117.

In one embodiment according to the invention, tubular shaft 24 andhandle 110 are designed in such a manner that tubular shaft 24 may bedetachably inserted into handle 110. To achieve this, a receivingopening 112, which can be closed by means of a cover, is located on theside of handle 110.

Thus, prior to the operation, a sterile disposable tubular shaft 24having appropriate tool head 30 and cutting device 50 is inserted intoreusable handle 110 and locked therein. Reuse of tubular shaft 24 andthe associated devices is not envisaged. Handle body 117 has a firstcoupling element 114 or a coupling element, a second coupling element114′ or a coupling element and a third coupling element 114″ or acoupling element for mechanical connection of tool head 30, cuttingdevice 51 and tubular shaft 24. A ring provided on the proximal end oftubular shaft 24 engages with third coupling element 114″ in such amanner that the tubular shaft is rigidly connected to handle body 117. Afirst inner tube adapter 22 engages, by means of a ring likewisedisposed on the proximal end, with first coupling element 114, which isin operative connection with second handle lever 122′. The displacementof second handle lever 122′ is transferred to first coupling element 114by means of a mechanism disposed inside handle body 117 and transfersthis displacement in turn to first inner tube adapter 22. This isdirectly or indirectly joined mechanically to second mouth part 10′ byway of tension strip 27. A longitudinal displacement of first inner tubeadapter 22 in relation to tubular shaft 24 thus brings about opening andclosing of mouth parts 10, 10′.

A second inner tube adapter 22′ is disposed movably in relation to firstinner tube adapter 22 inside said first inner tube. This inner tubeadapter 22′ is operatively connected to guide wire 52 and displacesblade 51. Inserting tubular shaft 24 into handle body 117 engages aproximal ring on the end of second inner tube adapter 22′ with secondcoupling element 114′ and transfers the displacement or the forceexerted by means of finger trigger 130 to cutting device 50.

In order to make it easier to insert disposable tubular shaft 24, aremovable fastening is provided thereon, which holds inner tube adapter22, 22′ in a predetermined position relative to tubular shaft 24, whichis designed in such a manner that the rings are easily insertable intocoupling elements 114, 114′, 114″.

Coupling elements 114, 114′, 114″ are designed in such a manner thattubular shaft 24 may be rotated in relation to handle 110. Thus thealignment of tool head 30 can be adjusted freely in relation to handle110. During rotation, the rings of inner tube adapters 22, 22′ and oftubular shaft 24 rotate in coupling elements 114, 114′, 114″ and thusform an articulation.

LIST OF REFERENCE NUMBERS

-   1 Fulcrum-   2 Abutting edge-   10, 10′ Mouth part-   12, 12° Clamping surface-   16, 16′ Tip-   20 Tubular shaft instrument-   22, 22′ Inner tube adapter-   24 Tubular shaft-   25 Adapter-   27 Tension strip-   30 Tool head-   40 Articulation-   41, 41′ Articulation guide rail-   42, 42′ Articulation guide pin-   43, 43′ Concave section of the articulation guide rail-   44, 44′ Convex section of the articulation guide rail-   46, 46′ Articulation guide bearing-   47 Tension strip pin-   50 Cutting device-   51 Blade-   52 Guide wire-   53 Blade guide-   54 Blade curvature-   55 Ramp-   56 Crimp-   60, 60′. Side part-   100 Processing unit-   101 Display device-   102 Travel sensor-   103 Switch-   110 Handle-   112 Receiving opening-   114, Coupling element-   116 Momentary contact switch-   117 Handle body-   120 Hand trigger-   122, Handle lever-   124 Toothed rack-   125 Extension-   130 Finger trigger-   x x-axis-   y y-axis-   z z-axis

1. A tubular shaft instrument for gripping and/or coagulating and/orseparating tissue, comprising: a tubular shaft; a first and a secondmouth part on a distal end of the tubular shaft each having at least oneclamping surface; at least one articulation for rotatably supporting themouth parts in such a manner that the mouth parts may be brought from anopen position into a closed position in order to fix the tissue usingthe clamping surfaces; and a strip that can be displaced substantiallylinearly for opening and closing of the first mouth part, the stripbeing attached by means of a resilient end section to the first mouthpart, wherein the articulation includes a slotted guide system, whereinthe slotted guide system is configured so that a virtual fulcrum of thearticulation is located at a distance from the longitudinal axis of thetubular shaft and the distal end of the first mouth part is displaceableaway from the distal end of the tubular shaft on opening the mouthparts, and wherein the first mouth part rotates around the virtualfulcrum on opening of the first mouth part.
 2. The tubular shaftinstrument according to claim 1, wherein the articulation includes anarticulation guide on one of the two mouth parts and at least one railor groove on the other of the two mouth parts.
 3. The tubular shaftinstrument according to claim 1, wherein the at least one articulationcomprises at least two partial articulations which are spaced apart fromone another to form a passage disposed centrally between said partialarticulations.
 4. The tubular shaft instrument according to claim 1,further comprising a blade for separating the fixed tissue.
 5. Thetubular shaft instrument according to claim 4, wherein at least onemouth part includes a blade guide.
 6. The tubular shaft instrumentaccording to claim 1, wherein one of the two mouth parts is rigidlyconnected to the tubular shaft.
 7. The tubular shaft instrumentaccording to claim 1, wherein the strip is designed as a tension strip,the end section of which is permanently attached to the mouth part. 8.The tubular shaft instrument according to claim 7, wherein the strip iscomprised of spring steel.
 9. The tubular shaft instrument according toclaim 1, wherein at least one of the clamping surfaces includes anelectrode for coagulation of the fixed tissue.
 10. The tubular shaftinstrument according to claim 1, wherein at least one of the mouth partscomprises, at least in the region of the articulation, an electricallyinsulating material.
 11. The tubular shaft instrument according to claim10, wherein the electrically insulating material is a ceramic material.12. The tubular shaft instrument according to claim 1, wherein one ofthe two mouth parts comprises a blade guide extending along the cuttingdirection.
 13. The tubular shaft instrument according to claim 12,wherein the blade guide is a ramp-shaped blade guide which is disposedsuch that, by moving in the direction of cutting, the blade guide bringsa blade out of a starting position at a distance from a fixing planeonto the fixing plane.
 14. The tubular shaft instrument according toclaim 12, wherein the blade guide is configured such that a blade may bebrought into a starting position close to the fulcrum of the mouthparts.
 15. The tubular shaft instrument according to claim 1, whereinthe tissue is fixed by means of the clamping surface in a fixing plane,whereby a cutting device having a blade for cutting tissue is disposedopposite one of the mouth parts and is displaceable over apredeterminable cutting path substantially parallel to the fixing plane.16. The tubular shaft instrument according to claim 15, furthercomprising a first electrode and a second electrode disposed in such amanner on the cutting device and/or the clamping surface that amechanical contact between blade and clamping surface is ascertainableby means of a processing unit connected to the electrodes.
 17. Thetubular shaft instrument according to claim 1, wherein the tubular shaftinstrument is an electrosurgical tubular shaft instrument.
 18. A tubularshaft instrument for gripping and/or coagulating and/or separatingtissue, comprising: a tubular shaft; a first and a second mouth part ona distal end of the tubular shaft each having at least one clampingsurface; at least one articulation for rotatably supporting the mouthparts in such a manner that the mouth parts may be brought from an openposition into a closed position in order to fix the tissue using theclamping surfaces; and a strip that can he displaced substantiallylinearly for opening and closing of a mouth part to be displaced, saidstrip being attached by means of a resilient end section on the mouthpart to be displaced, wherein the articulation is configured so that afulcrum of the articulation is located outside the mouth parts and thedistal end of at least one mouth part is displaceable away from thedistal end of the tubular shaft on opening of the mouth parts, andwherein the strip is attached to the mouth part by means of welding. 19.The tubular shaft instrument according to claim 18, wherein the strip isattached to the mouth part via a welding joint that is square inrelation to a longitudinal axis of the strip.
 20. The tubular shaftinstrument according to claim 18, wherein the strip is attached to themouth part via a welding joint that is curved in relation to alongitudinal axis of the strip.
 21. A tubular shaft instrument forgripping and/or coagulating and/or separating tissue, comprising: atubular shaft; a first and a second mouth part on a distal end of thetubular shaft each having at least one clamping surface; and at leastone articulation for rotatably supporting the mouth parts in such amanner that the mouth arts may be brought from an open position into aclosed position in order to fix the tissue using the clamping surfaces,wherein the articulation is configured so that a fulcrum of thearticulation is located outside the mouth parts and the distal end of atleast one mouth part is displaceable away from the distal end of thetubular shaft on opening of the mouth parts, wherein the mouth parts areconfigured to fix a tissue in a fixing plane, the tubular shaftinstrument further comprising: a cutting device having a blade forcutting the fixed tissue, the cutting device being displaceable in acutting direction by means of an actuating device, the blade configuredto be displaceably guided substantially parallel to the fixing plane andpreloaded against the fixing plane during cutting by means of apreloading device, and wherein the preloading device comprises aresilient guide wire having a curvature, whereby the guide wire issubstantially rigidly joined to the blade and is guided in the tubularshaft in such a manner that the blade is preloaded in relation to thetubular shaft in the direction of the fixing plane.
 22. The tubularshaft instrument according to claim 21, wherein the preloading deviceincludes a crimp which is disposed in the guide wire such that the crimpis close to the distal end of the tubular shaft when the blade is pushedforward.
 23. A tubular shaft instrument for gripping and/or coagulatingand/or separating tissue, comprising: a tubular shaft; a first and asecond mouth part on a distal end of the tubular shaft each having atleast one clamping surface; and at least one articulation for rotatablysupporting the mouth parts in such a manner that the mouth parts may bebrought from an open position into a closed position in order to fix thetissue using the clamping surfaces, wherein the articulation isconfigured so that a fulcrum of the articulation is located outside themouth parts and the distal end of at least one mouth part isdisplaceable away from the distal end of the tubular shaft on opening ofthe mouth parts, wherein the mouth parts are configured to fix a tissuein a fixing plane, the tubular shaft instrument further comprising: acutting device having a blade for cutting the fixed tissue, the cuttingdevice being displaceable in a cutting direction by means of anactuating device, the blade configured to be displaceably guidedsubstantially parallel to the fixing plane and preloaded against thefixing plane during cutting by means of a preloading device, and whereinthe preloading device includes a crimp which is disposed in the guidewire such that the crimp is close to the distal end of the tubular shaftwhen the blade is pushed forward.
 24. A medical instrument, comprising:a tubular shaft; a first and a second mouth part on a distal end of thetubular shaft, each having at least one clamping surface; at least onearticulation for rotatably supporting the mouth parts in such a mannerthat the mouth parts may be brought from an open position into a closedposition in order to fix a tissue in a fixing plane using the clampingsurfaces; a strip that can be displaced substantially linearly foropening and closing of the first mouth part, the strip being attached bymeans of a resilient end section to the first mouth part; a cuttingdevice having a blade for cutting tissue and is disposed opposite one ofthe mouth parts and is displaceable over a predeterminable cutting pathsubstantially parallel to the fixing plane; and a first electrode and asecond electrode disposed in such a manner on the cutting device and/orthe clamping surface that a mechanical contact between blade andclamping surface is ascertainable by means of a processing unitconnected to the electrodes, wherein the articulation includes a slottedguide system, wherein the slotted guide system is configured so that avirtual fulcrum of the articulation is located at a distance from thelongitudinal axis of the tubular shaft and the distal end of the firstmouth part is displaceable away from the distal end of the tubular shafton opening the mouth parts, wherein the first mouth part rotates aroundthe virtual fulcrum on opening of the first mouth part, and wherein theblade comprises the first electrode, the clamping surface comprises thesecond electrode and the processing unit comprises a device fordetermining an electrical resistance between the electrodes.
 25. Themedical instrument according to claim 24, wherein the processing unit isconfigured so that a curve of the resistance is ascertainable during thecutting path.
 26. The medical instrument according to claim 24, whereinthe processing unit comprises a travel sensor and/or an electric switchfor detecting the displacement of the blade parallel to the clampingsurface.